Orthopaedic splinting material

ABSTRACT

A colored orthopedic splinting material comprising a glass fiber substrate and a hardenable resin wherein the individual filaments making up the substrate are colored.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a hardenable material which comprises asubstrate carrying a hardenable resin, for example which hardens oncontact with water. More specifically, this invention relates to acolored orthopaedic splinting material which carries a hardenable resin.

2. Description of Related Art

It is well established to use water hardenable isocyanate functionalresins in orthopaedic splint bandages. Such bandages are disclosed inBritish Patent No. GB2216533.

For some considerable time now it has been desirable to use coloredcasting materials which includes for example solid colours, prints andmulticolored decorations. Methods of colouring casting materials aredisclosed in U.S. Pat. No. 5,476,438. However such casts suffer from thedisadvantage that the colored prepolymers will readily stain othermaterial with which they come into contact. Methods of overcoming thisdisadvantage are disclosed in European Patent Application No. 479269 andPCT Application No. WO93104709. Both applications generally relate tothe manufacture of colored orthopaedic casts or multicolored orthopaediccasts by printing one or more pigments onto the surface of a knittedsubstrate which results in the coating or partial coating of some of theyarns but not the individual filaments. In addition, such printingtechniques prove to be expensive in manufacture, inter alia, because ofthe need to clean machinery when changing production from one color toanother. It is also a method which does not lend itself well tocontinuous production and generally requires a batch process.

A preferred material from which casting substrates can be formed areglass fibre yarns. Glass fibre yarns are conventionally manufactured bydrawing molten glass through nozzles to form filaments. The filamentsare cooled, sized and gathered to form glass fibre strands. The glassfibre strands are subsequently twisted and plied to form glass fibreyarns.

BRIEF SUMMARY OF THE INVENTION

Glass fibre yarns can be woven or knitted into casting substrates usingsimilar processes as are used in textile operations.

In the electronics industry it has been known for nearly twenty years tocoat wires with yarns manufactured from colored fibre glass filaments.Such yarns comprise individual filaments which are completely coatedwith a dye.

We have now found that such coloured yarns may also be used in themanufacture of colored substrates for use in orthopaedic casting. Thussuch colored yarns may be used to produce colored, multicolored orpatterned substrates for use in orthopaedic casting.

Thus it is novel to knit such colored yarns into a substrate or fabricwhich may be suitable for use as an orthopaedic splinting material.

According to the invention we provide a colored knitted or wovensubstrate comprising glass fibre yarns wherein the glass fibre yarnscomprise a plurality of individual colored filaments. Preferably saidsubstrate is a knitted substrate.

According to the invention we further provide a colored orthopaedicsplinting material comprising a substrate carrying a hardenable resinwherein said substrate comprises glass fibre yarns characterised in thatthe glass fibre yarns comprise a plurality of individual coloredfilaments.

In a preferred embodiment of the invention the colored glass fibresubstrate which comprises glass fibre yarns wherein the glass fibreyarns comprise a plurality of individual colored filaments isconformable.

Conformability of the substrate is achieved through knitting or weavingthe colored glass fibre yarns, preferably the colored glass fibre yarnsare knitted into a conformable, relatively stretchable substrate.

The substrate may be any colored glass fibre fabric which has theproperties required for use as an orthopaedic bandage as regards toextensibility and strength. The glass fibre fabrics may be available intwo knit-types namely a Raschel knit and a tricot knit.

The substrate is preferably in the form of a bandage but other forms ofsheet materials, for example those to form slabs, are also envisaged.The glass fibre substrate may, in addition to glass fibre yarns, becomposed of one or more natural or synthetic fibres conventionally usedto form a plastic orthopaedic cast. The fibres can include cotton,nylon, polyester, acrylic and the like.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

According to the present invention we therefore provide a coloredorthopaedic splinting material as hereinbefore described wherein thesubstrate is in the form of a bandage.

The coloured substrate of the invention is particularly advantageous inthat it may carry a hardenable resin to produce an orthopaedic splintingmaterial.

The substrate may carry the hardenable resin in a number of conventionalways per se and the substrate may for example be coated, impregnated orsprayed with the hardenable resin. In a preferred embodiment thesubstrate is coated with the hardenable resin.

The hardenable resin is preferably a water hardenable resin andespecially an isocyanate functional resin. Aptly the resin used to coatthe glass fibre substrate may be a cold water curable isocyanateterminated polyurethane prepolymer system. Among suitable polyurethaneprepolymer systems are those identified in U.S. Pat. Nos. 4411262,4427002, 4433680 and 4574793. Particularly preferred are those systemsdisclosed and claimed in U.S. Pat. Nos. 4,427,002 and 4,574,793.Particularly preferred resins are also those disclosed in British PatentNo. GB2216533 and the whole of that document is intended to beincorporated herein by reference.

Thus according to the invention we further provide a colored orthopaedicsplinting material as hereinbefore described comprising a substratecarrying a hardenable resin wherein the hardenable resin is anisocyanate functional resin.

In a further embodiment of the invention we provide a coloredorthopaedic splinting material as hereinbefore described wherein thehardenable resin is a polyurethane prepolymer.

In a most preferred embodiment of the invention we provide a coloredorthopaedic splinting material as hereinbefore described wherein thehardenable resin is a water hardenable resin.

Various known additives can be incorporated into the resin such as, forexample, viscosity modifiers, uv stabilizers and/or antioxidants. Wheredesirable, various dyestuffs can also be incorporated into the resin inorder to provide different colour effects for the resulting cast. Theinvention is also particularly useful in combination with resins otherthan the water curable polyurethane resins. For example, the castingmaterials of the invention can be used in combination with two componentresin systems, such as epoxy based systems, unsaturated polyestersystems and polyurethane systems where the isocyanate is maintainedseparately from the polyol. In such systems, the glass fibre substrateis maintained separately from one or both of the resin reactants untiljust prior to use. The glass fibre substrate may thus be packageduncoated, or coated with only one component of the system and rolledinto a roll. A separate portion of the pouch, or a separate pouch,contains either the second resin component or the liquid resin. Justprior to using the casting material to form a cast on the limb of apatient, the physician or cast technician applies the resin material orthe second component thereof to the roll in order to initiate hardeningof the resin.

The glass fibre filaments may be coloured by any conventional methodsknown per se. These include for example melting certain transition metalions into a glass, the precipitation of coloured crystals which dissolvein glass at high temperatures and precipitate on cooling, the use ofpigments, stains and dyes.

In a preferred embodiment of the present invention the glass fibre yarnscomprise a plurality of individual colored filaments wherein thefilaments are dyed. Any conventional dyeing method may be used.Preferably the colored glass fibre yarns are colorfast to light and havea high heat stability.

Any conventional dyes known to be suitable for application to glassfibre filaments may be used for example inorganic high temperature dyesor acrylic dyes. However, preferred dyes are those which do not interactwith the resin and especially those which do not react within isocyanateresins. Preferred dyes are especially acrylic dyes.

The glass fibre substrate may consist of yarns comprising a plurality ofindividual colored filaments wherein the filaments may comprise a numberof colors. Colored filaments may be mixed with filaments that have notbeen colored to achieve a desired shade or decorative effect for thesubstrate.

The use of differently colored filaments to prepare differently coloredglass fibre yarns allows the incorporation of decorative patterns andmotifs into the substrate. Two or more colored glass fibre yarns may betwisted together to produce multicoloured yarns.

Each glass fibre filament may be of a uniform color or may be coloredwith several colors or may be of a non-uniform color.

According to the invention we provide a method of preparation of acolored orthopaedic splinting material as hereinbefore described whichcomprises knitting or weaving a substrate from colored glass fibrefilament yarns followed by coating or impregnating the substrate with ahardenable resin.

In a preferred embodiment of the invention we provide a method ofpreparation of a colored orthopaedic splinting material as hereinbeforedescribed which comprises knitting a substrate from colored glass fibrefilament yarns followed by coating the substrate with a hardenableresin.

Any suitable coating means can be used to coat the substrate with aresin including fixed doctor blade over flat bed, or roller and rollercoating systems.

It is desirable that the resin during coating is protected fromexcessive moisture vapour. Suitable coating systems can be enclosed andcan be conducted in an atmosphere free from excessive moisture vapoursuch as dry air, or inert gases for example carbon dioxide or nitrogen.

In a preferred continuous process the resin in liquid form is coated onto a length of the substrate by means of a blade over flat bed and thecoated substrate by means of a blade over flat bed and the coatedsubstrate dried, if necessary. The coated substrate can then be splitinto suitable sized strips and rolled up into bandages.

The amount of resin on the substrate should be sufficient to ensure thatthe resultant splint has adequate strength. Suitable amounts have beenfound to be 50 to 500 gm², preferably 100 to 305 g/m², for example 200g/m², 250 g/m² or 300 g/m².

Preferably, the splinting bandages should be protected during storagefrom water and excessive moisture vapour to prevent a premature settingtaking place, the bandages can be conventionally packaged in heat sealedwaterproof pouches such as metal foil polyethylene laminate orpolyethylene pouches.

In use the splinting bandages may be brought into contact with water andwrapped around the injured part of the body. The splinting bandage has aworking time which is sufficient to allow the bandage to be positioned,and a set time which is the time taken for the splinting material tobecome rigid. Favoured working times are 1 minute to 6 minutes andespecially 2 minutes to 4 minutes. Favoured set times are 5 minutes to30 minutes and especially 6 minutes to 15 minutes.

It is novel to use dyed fibre glass yarns in orthopaedic splintingmaterials. Thus according to the invention we provide the use of glassfibre yarns comprising a plurality of individual coloured filaments inthe manufacture of a substrate for use in the preparation of a coloredorthopaedic splint.

We further provide a method of forming a colored orthopaedic splint ofthe present invention which comprises positioning a splinting materialabout a member to be immobilized said splinting material being adaptedto set by polymerisation of a hardenable resin and thereafter causingthe material to set by curing the resin.

In a further embodiment we provide a method of forming a coloredorthopaedic splint of the present invention which comprises positioninga splinting material about a body part to be immobilised said splintingmaterial being adapted to set by polymerisation of a water hardenableresin and causing the splinting material to set by introducing water tothe splinting material.

According to the present invention we in addition provide a method fortreating a fracture of a body part which comprises applying a coloredorthopaedic splinting material as hereinbefore described to said bodypart and causing the splinting material to set by curing the hardenableresin.

The present invention is advantageous in that it provides, inter alia,method for material colored hardenable orthopaedic materials which isless expensive or less messy than known methods.

Orthopaedic splints may be prepared which comprise yarns of a singlecolour or yarns of different colors may be knitted together to providemulticolored materials.

The dyed glass fibre yarns for use in the present invention areavailable from Polux Limited of Rochdale in the United Kingdom.

The invention will now be illustrated but in no way limited by thefollowing Example.

EXAMPLE 1

A water curable polyurethane resin system comprising a polyurethaneprepolymer described in U.S. No. 4,574,793 as prepolymer A andcontaining methane sulphonic acid as stabiliser and bis(2,6dimethylmorpholino)diethyl ether as catalyst was coated onto anuntreated coloured knitted glass fibre fabric substrate comprising yarnsof individual colored filaments using the process described in U.S. Pat.No. 4,427,002. The resin-coated colored glass fibre substrate was woundonto a master roll which is approximately 25 cm in width and is 500 m inlength.

I claim:
 1. A colored orthopaedic splinting material comprising asubstrate carrying a hardenable resin wherein said substrate comprisesyarns characterized in that the yarns comprise a plurality ofindividually colored filaments.
 2. A colored orthopaedic material asclaimed in claim 1 wherein the yarns comprise glass fibre yarns.
 3. Acolored orthopaedic splinting material as claimed in claim 1characterized in that the hardenable resin comprises a water hardenableresin.
 4. A method of forming a colored orthopaedic splint whichcomprises positioning a splinting material as claimed in claim 3 about abody part to be immobilized, said splinting material being adapted toset by polymerization of said water hardenable resin, and causing thesplinting material to set by introducing water to the splintingmaterial.
 5. A colored orthopaedic splinting material as claimed inclaim 1 characterized in that the hardenable resin comprises anisocyanate functional resin.
 6. A colored orthopaedic splinting materialas claimed in claim 1 characterized in that the hardenable resincomprises a polyurethane prepolymer.
 7. A colored orthopaedic splintingmaterial as claimed in claim 1 characterized in that the substrate is inthe form of a bandage.
 8. A colored orthopaedic splinting material asclaimed in claim 1 characterized in that the filaments are dyed.
 9. Amethod of preparation of a colored orthopaedic splinting materialaccording to claim 1 which comprises knitting or weaving a substratefrom colored filament yarns followed by coating or impregnating thesubstrate with a hardenable resin.
 10. A method for treating a fractureof a body part which comprises applying a colored orthopaedic splintingmaterial as claimed in claim 1 to the body part, and causing thesplinting material to be set by curing the hardenable resin.